WO2006008929A1

WO2006008929A1 - Fuel cell cathode manufacturing method and fuel cell manufacturing method

Info

Publication number: WO2006008929A1
Application number: PCT/JP2005/011966
Authority: WO
Inventors: Atsushi Sano; Satoshi Maruyama
Original assignee: Tdk Corporation
Priority date: 2004-06-30
Filing date: 2005-06-29
Publication date: 2006-01-26
Also published as: TW200618384A; US20070167313A1; JPWO2006008929A1; US7927762B2

Abstract

There is provided a fuel cell cathode manufacturing method which is a method for manufacturing a fuel cell cathode including a catalyst layer containing catalyst. The method includes a potential application process for forming the catalyst layer by applying noble potential higher than 1.3V, assuming the standard hydrogen electrode as a reference, to a precursor layer containing the catalyst.

Description

Specification

Method for producing power sword for fuel cell and method for producing fuel cell

Technical field

The present invention relates to a method for manufacturing a fuel cell power sword and a method for manufacturing a fuel cell.

Background art

In recent years, fuel cells are attracting attention as an energy supply source in which the reaction product with high power generation efficiency is only water in principle and has excellent environmental properties. Depending on the type of electrolyte used, such a fuel cell may be a low temperature operation fuel cell such as an alkaline type, a solid polymer type, or a phosphoric acid type, and a high temperature operation fuel cell such as a molten carbonate type or a solid oxide type. It is roughly divided into In particular, a polymer electrolyte fuel cell (PEFC) using a solid polymer as an electrolyte can achieve high density and high output with a compact structure, and can be operated with a simple system. Therefore, it has been widely researched not only for stationary distributed power sources but also for power sources for vehicles, etc. and is expected to be put to practical use.

[0003] As one of such PEFCs, there is a direct alcohol fuel cell that uses alcohol as a direct fuel, especially a direct methanol fuel cell (DMFC) that uses methanol as the fuel. It has been known. In DMFC, when methanol and water are supplied to the anode (fuel electrode), methanol is oxidized by water and hydrogen ions are generated. The hydrogen ions move through the electrolyte and reach the force sword (air electrode), which is supplied to the cathode to reduce oxygen. Based on these redox reactions, current flows between the two electrodes.

[0004] As described above, since the direct alcohol fuel cell can be directly used for power generation without reforming the alcohol as a fuel into hydrogen or the like, it is not necessary to provide a separate fuel reforming device. It will have a structure. For this reason, the direct alcohol fuel cell is extremely easy to reduce in size and weight, and can be suitably used for portable power supply applications and the like.

[0005] The anode and force sword of these PEFCs are composed of, for example, two layers of a catalyst layer serving as a reaction field for electrode reaction and a diffusion layer for supplying reactants to the catalyst layer, transferring electrons, etc. The As a catalyst contained in the catalyst layer, a noble metal such as platinum or a noble metal alloy is generally used.

[0006] Among noble metals, platinum is widely used as a force sword catalyst because it can maximize the current density of oxygen reduction when an electrode is formed and is stable even at a high potential. As an anode catalyst, an alloy of platinum and another metal is widely used.

[0007] However, since platinum is expensive, it is a major obstacle to cost reduction and mass production for the spread of fuel cells. In view of this, a catalyst that replaces platinum has been studied. For example, Patent Document 1 describes the use of a mixture of a metal complex and a metal oxide as a force sword catalyst. And it is described that the 4-electron reduction reaction of oxygen proceeds apparently.

Patent Document 1: JP 2003-151567 A

Disclosure of the invention

Problems to be solved by the invention

However, when the catalyst described in Patent Document 1 is used as a force sword, it is difficult to obtain a sufficient current density that is significantly lower than that when platinum is used. There is a problem that.

[0009] In addition, even when platinum is used as a catalyst, it cannot be said that the current density is sufficiently high, and further improvement of the current density is desired even in such an electrode.

[0010] The present invention has been made in view of the above-described problems of the prior art, and a method of manufacturing a fuel cell cathode capable of improving the current density per unit area of an electrode in a fuel cell. And it aims at providing the manufacturing method of a fuel cell.

Means for solving the problem

[0011] In order to achieve the above object, the present invention provides a method for producing a power sword for a fuel cell comprising a catalyst layer containing a catalyst, wherein the precursor layer containing the catalyst is based on a standard hydrogen electrode. 1. A method for producing a power sword for a fuel cell, comprising a potential application step of forming a catalyst layer by applying a potential nobler than 3 V.

[0012] According to the powerful manufacturing method, the catalytic activity can be improved by applying a potential to the precursor layer containing the catalyst in the potential applying step. Thus, the catalyst activity The present inventors speculate that the improvement in the property is due to the oxidation of impurities in the precursor layer by applying a potential and the improvement in the conductivity of the catalyst. By improving the catalytic activity, it is possible to improve the current density of the electrode (current density per unit electrode area when the fuel cell is constructed and used). Furthermore, since the inherent potential of the force sword can be increased by the potential application step, the cell voltage can be improved.

[0013] In the potential application step, it is preferable to apply a potential of 1.6 V or less to the precursor layer with reference to a standard hydrogen electrode.

[0014] By applying such a potential, the catalyst can be more activated and the current density tends to be further improved. In addition, the cell voltage tends to be further improved by increasing the potential of the force sword. When this potential is 1.3 V or less, the activation of the catalyst is insufficient and the current density is insufficiently improved. When the potential exceeds 1.6 V, the catalyst is oxidatively decomposed and the catalytic activity is immediately reduced. .

[0015] In addition, in the potential application step, it is preferable to apply a potential to the precursor layer by a potential sweep. By applying a potential to the precursor layer by potential sweeping, the catalyst can be activated efficiently and sufficiently, and the current density of the electrode can be more sufficiently improved.

[0016] In the above production method, the catalyst is preferably a metal complex and Z or a fired metal complex obtained by firing the metal complex.

[0017] The effect of improving the catalytic activity by the production method of the present invention can be obtained particularly effectively when a metal complex and Z or a fired product of a metal complex are used as a catalyst. This is considered to be because, by applying a potential, the valence of the central metal of the metal complex and Z or the fired product of the metal complex takes a highly oxidized state and the catalytic activity is improved. Therefore, when a metal complex and Z or a fired product of a metal complex are used as a catalyst, the current density of the electrode can be dramatically improved.

[0018] Further, the metal complex preferably has a porphyrin ring or a phthalocyanine ring.

[0019] When a metal complex and / or a fired metal complex formed by firing the metal complex is used. In addition, the catalytic activity can be remarkably improved by the potential application step, and the current density of the electrode can be remarkably improved. In addition, the activation of the catalyst improves the cycle characteristics, and an electrode with high output and high stability can be obtained. Such an effect can be obtained by doping the crystalline or amorphous porphyrin layer hair dione in the potential application step to significantly improve the conductivity, or by rearranging the porphyrin layer by applying the potential, and thereby effective ions and ions. The present inventors infer that it is obtained by forming an electron conductive path.

[0020] Furthermore, in order to obtain the above-described effect more efficiently, the metal complex is composed of at least one metal selected from the group consisting of Co, Fe, Ni, Cu, Mn, V and Ru as a central metal. It is preferable that

[0021] Further, in the above production method, the precursor layer is formed by a coating method using a coating solution composed of the catalyst and a solvent capable of dissolving or dispersing the catalyst before the potential application step. It is preferable to include a body layer forming step. By forming the precursor layer by a coating method, the effect of improving the catalytic activity by the potential application step can be more sufficiently obtained, and the current density of the electrode can be more sufficiently improved.

[0022] The present invention is also a method for producing a fuel cell comprising an anode, a force sword, and a solid polymer electrolyte membrane disposed between the anode and the force sword. The present invention also provides a method for producing a fuel cell, comprising an electrode forming step formed by the method for producing a power sword for a fuel cell of the present invention.

[0023] According to the method for manufacturing a fuel cell, since the force sword is formed by the method for manufacturing the force sword of the present invention, the current density of the obtained fuel cell is improved, and the fuel cell system is improved. The energy density can be sufficiently improved. In addition, the cell voltage can be improved sufficiently.

The invention's effect

[0024] According to the present invention, it is possible to provide a method for producing a fuel cell power sword capable of improving the current density and a method for producing a fuel cell capable of improving the energy density.

Brief Description of Drawings FIG. 1 is a schematic cross-sectional view showing a fuel cell including a cathode obtained by a preferred embodiment of a method for producing a power sword for a fuel cell of the present invention.

FIG. 2 is a graph showing the relationship between the potential and the current density in the potential sweep at the 50th cycle in Example 1.

FIG. 3 is a graph showing the relationship between the potential and the current density in the potential sweep at the 50th cycle in Example 2.

FIG. 4 is a graph showing the relationship between potential and current density in each electrode of Example 1 and Comparative Example 1.

Explanation of symbols

[0026] 1 ... solid polymer electrolyte membrane, 2 ... anode catalyst layer, 3 ... force sword catalyst layer, 4a, 4b ... gas diffusion layer, 5 ... separator, 5a ... gas supply groove of separator 5, 6 ... gas sheath body, 10 ··· Fuel cell.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and duplicate descriptions are omitted.

FIG. 1 is a schematic cross-sectional view showing a fuel cell including an electrode obtained by a preferred embodiment of the method for producing a power sword for a fuel cell of the present invention. The fuel cell 10 shown in FIG. 1 has a so-called membrane electrode assembly (MEA) form. A fuel cell 10 shown in FIG. 1 mainly includes a solid polymer electrolyte membrane 1, an anode catalyst layer 2 and a force sword catalyst layer 3 that are in close contact with the membrane surface of the electrolyte membrane 1, and an outer surface of the anode catalyst layer 2. The gas diffusion layer 4a is in close contact, the gas diffusion layer 4b is in close contact with the outer surface of the force sword catalyst layer 3, and the gas seal body 6. Further, on the outside of the gas diffusion layers 4a and 4b, separators 5 each having a groove 5a serving as a flow path for reactants to be supplied to the gas diffusion layers 4a and 4b are formed. .

[0029] In the fuel cell 10, the anode 20 is composed of the anode catalyst layer 2 and the gas diffusion layer 4a, and the force sword 30 is composed of the force sword catalyst layer 3 and the gas diffusion layer 4b. The gas diffusion layer 4a and the gas diffusion layer 4b in the anode 20 and the force sword 30 are usually porous. Made of a conductive base material. Each of the diffusion layers 4a and 4b is not an essential component in the fuel cell 10, but promotes the diffusion of fuel into the anode catalyst layer 2 and the diffusion of gas into the force sword catalyst layer 3, and functions as a current collector. Therefore, it is preferable that the anode 20 and the force sword 30 are provided with the respective diffusion layers 4 and 5.

Hereinafter, a preferred embodiment of a method for producing the force sword 30 in the fuel cell 10 will be described.

[0031] The method for producing a force sword according to the present invention is a method characterized in that the force sword catalyst layer 3 is formed through a potential applying step. This potential application step is a step of applying a potential to the precursor layer that is the precursor of the force sword catalyst layer 3.

First, the precursor layer will be described. The precursor layer is a layer containing a catalyst to be contained in the force sword catalyst layer 3. As long as the catalyst is contained, the configuration is not particularly limited. For example, the configuration includes only the catalyst, the configuration including the catalyst and an ion exchange resin capable of binding the catalyst, and the catalyst as a carbon material. Examples include a configuration including a supported catalyst and an ion exchange resin.

[0033] Here, examples of the catalyst include precious metals, precious metal alloys, metal complexes, and fired metal complexes formed by firing a metal complex.

[0034] An example of the noble metal is Pt. Examples of the noble metal alloy include alloys of Pt and Ru, Sn, Mo, Ni, Co and the like.

[0035] Examples of the metal complex include metal phthalocyanines such as iron phthalocyanine, cobalt phthalocyanine, copper phthalocyanine, mangan phthalocyanine, and zinc phthalocyanine, iron tetraphenyl porphyrin, copper tetraphenylporphyrin, zinc tetraphenylporphyrin, cononorte tetraphenyl. Examples thereof include metal porphyrins such as porphyrins, metal complexes such as ruthenium ammine complexes, cobaltamine complexes, and cobalt ethylenediamine complexes. Among these, it is preferable that the metal complex has a porphyrin ring or a phthalocyanine ring. Furthermore, the metal complex mainly includes at least one metal selected from the group consisting of Co, Fe, Ni, Cu, Mn, and V. More preferably, it is a metal.

[0036] Examples of the fired metal complex include those obtained by firing the above metal complexes, and those obtained by firing a metal complex having a borphyrin ring or a phthalocyanine ring are preferred. It is more preferable to fire a metal complex having at least one metal selected from the group consisting of e, Ni, Cu, Mn and V as a central metal.

[0037] Here, in the case of obtaining a fired metal complex, the fired metal complex can be performed by treatment in an inert atmosphere at 500 to 800 ° C for 1 to 20 hours. In the case of using the above-mentioned supported catalyst, it is preferable to carry out calcination after the metal complex is supported on the carbon material. This tends to make it possible to obtain a supported catalyst in which the fired metal complex is in a highly dispersed state and is in close contact with the carbon material. When such a supported catalyst is used, the three-phase interface in which the reactant, the catalyst, and the electrolyte membrane 1 are present simultaneously can be increased, so that the electrode reaction can be improved. ] Can be generated efficiently.

[0038] Among these catalysts, it is preferable to use a metal complex and / or a fired product of a metal complex in the present invention. When a metal complex and / or metal complex fired product is used, the current density is greatly increased because the valence of the central metal of the metal complex and / or metal complex fired product takes a highly oxidized state due to potential application and the catalytic activity is improved. Can be improved. In particular, when the preferred ones mentioned above are used among the metal complexes and / or the fired metal complex, the conductivity is greatly improved by doping the crystalline or amorphous porphyrin layer hairion by applying a potential. In addition, the rearrangement of the crystalline or amorphous vorphyrin layer by applying a potential will form an effective ion and electron conduction path, which can dramatically improve the current density. In addition, the activation of the catalyst improves the cycle characteristics, and an electrode having high output and high stability can be obtained.

[0039] From the viewpoint of forming a larger three-phase interface, the average particle size of these catalysts is preferably:! To 2 Onm.

[0040] When such a catalyst is supported on a carbon material, examples of the carbon material include carbon black, activated carbon, carbon nanotube, and carbon nanohorn. Among these, carbon black is preferable. When carbon black is used as the carbon material, the specific surface area is preferably 250 to 1000 m ² Zg from the viewpoint of forming a larger three-phase interface. From the same viewpoint, the average primary particle diameter of the carbon material is preferably 5 to 500 nm.

[0041] Further, in the supported catalyst, the supported amount of the catalyst is 10 to 85 on the basis of the total amount of the supported catalyst. It is preferable that it is mass%. If the supported amount is less than 10% by mass, the amount of the catalyst in the catalyst layer is insufficient, and the three-phase interface tends to be insufficient. On the other hand, if the supported amount exceeds 85% by mass, the catalysts agglomerate and the catalytic activity tends to be reduced.

[0042] The ion exchange resin contained in the precursor layer as necessary functions as a binder for binding the supported catalyst. The strong ion exchange resin is not particularly limited as long as it can bind the supported catalyst, but has the same ion exchange property as the ion exchange resin used for the electrolyte membrane 1 constituting the fuel cell 10. It is preferable to have it. That is, it is preferable to use an anion exchange resin if the electrolyte membrane 1 is made of an anion exchange resin, and use a cation exchange resin if the electrolyte membrane 1 is made of a cation exchange resin. As a result, ion conduction is performed satisfactorily at the contact interface between the ion exchange resin, the catalyst, and the electrolyte membrane 1, and the energy density tends to be improved.

[0043] The anion exchange resin is preferably made of a polymer compound having a cationic group in the molecule. The cationic group is preferably at least one selected from the group consisting of a pyridinium group, an alkylammonium group, and an imidazolium group. Examples of such anion exchange resins include quaternary ammonia-treated poly-4-bulupyridine, poly-2-bulupyridine, poly-2-methyl-5-bulupyridine, poly_1_pyridine-l-ylcarbonyl. Roxyethylene etc. are mentioned. Here, the quaternary ammonium-forming treatment of poly (4-bulupyridine) can be carried out by reacting poly (4-bulupyridine) with an alkyl halide such as methyl bromide or bromide acetyl.

[0044] Further, as the cation exchange resin, for example, a perfluorocarbon polymer having a sulfonic acid group, a polysulfone resin, a perfluorocarbon polymer having a phosphonic acid group or a carboxylic acid group can be used.

[0045] The content of the ion exchange resin is preferably 10 to 50% by mass based on the total amount of the precursor layer.

[0046] When the precursor layer has a configuration composed only of a catalyst, the precursor layer can be formed by, for example, a vacuum deposition method or a coating method. When forming by a coating method, a coating solution comprising a catalyst and a solvent capable of dissolving or dispersing the catalyst is applied on the gas diffusion layer 4b. The precursor layer can be formed by applying and drying. As a coating method, a doctor blade method, a noznore method, screen printing, a gravure coat, a die coater, or the like can be employed.

[0047] When the precursor layer has a structure including a catalyst and an ion exchange resin, the precursor layer can be formed by, for example, the above-described coating method. The solvent used here is one that can dissolve or disperse the catalyst and can dissolve or disperse the ion exchange resin.

[0048] When the precursor layer has a structure including a supported catalyst in which a catalyst is supported on a carbon material and an ion exchange resin, the precursor layer can be formed by the following procedure, for example.

[0049] First, a supported catalyst is obtained by mixing a catalyst and a carbon material by a ball mill or the like. The mixing method can be appropriately selected and may be dry or wet. In the case of using a metal complex fired product as the catalyst, it is preferable to perform firing after mixing to obtain a supported catalyst.

[0050] Thereafter, a binder solution is prepared by dissolving or dispersing an ion exchange resin as a binder in a solvent, and a supported catalyst is placed in the binder solution, mixed, kneaded, and made into a paint. Here, kneading and coating can be performed by a commonly used kneader such as a ball mill, a twin-screw kneader, or a twin-screw extruder.

[0051] Then, the obtained paint is applied onto the gas diffusion layer 4b and dried to form a precursor layer. As a coating method, a doctor blade method, a nozzle method, screen printing, gravure coating, die coater or the like can be employed.

[0052] Here, the gas diffusion layer 4b is formed of, for example, a porous body having electron conductivity.

. As such a porous body, carbon cloth, carbon paper and the like are preferable.

[0053] The thickness of the gas diffusion layer 4b is preferably 10 to 300 zm.

[0054] Next, a potential application step for applying a potential to the precursor layer having the above-described configuration will be described.

[0055] In the potential application step, a force sword catalyst layer 3 is formed by applying a noble potential from 1.3 V to the precursor layer with reference to the standard hydrogen electrode. Here, the applied potential is 1.3V It is preferable that the potential is 1.6 V or less. 1.4 V to: 1. 6 V is more preferable.

[0056] Application of a potential to the precursor layer in the potential application step can be performed by, for example, potential sweeping, constant potential holding, constant current electrolysis, or the like.

[0057] When applying a potential by sweeping the potential, for example, the cutoff potential is set to 1.4 V and 1.6 V, and the potential is swept at a sweep rate of about 0.1 mVZs to 500 mV / s. Can be

[0058] In the case of applying a potential by holding a constant potential, for example, it can be activated by holding a potential at a constant potential of 1.5 V for a fixed time using a potentiostat.

[0059] When applying a potential by constant-current electrolysis, activation is performed by using a galvanostat charging / discharging device to pass a current that makes the force sword potential nobler than 1.3 V for a certain period of time. can do.

By performing such a potential application step, impurities in the precursor layer are removed by oxidation, and the conductivity of the catalyst is improved, so that the catalytic activity can be improved. Thereby, the current density of the obtained electrode can be improved. Also, the cell voltage can be improved by increasing the potential of the force sword. When the applied potential is 1.3 V or less, the activation of the catalyst is insufficient and the current density is insufficiently improved. When the applied potential exceeds 1.6 V, the catalyst is liable to undergo oxidative decomposition. .

[0061] Note that when the potential in the above range is applied to the precursor layer by the potential sweep, the maximum potential when performing the potential sweep is in the above range.

[0062] The formation of the fuel cell power sword is completed by forming the catalyst layer 3 by a strong potential application step.

Next, a method for manufacturing the fuel cell 10 will be described.

[0064] A method of manufacturing a fuel cell 10 includes a method of manufacturing a fuel cell including an anode 20, a force sword 30, and a solid polymer electrolyte membrane 1 disposed between the anode 20 and the force sword 30. A method comprising an electrode forming step of forming the force sword 30 by the above-described fuel cell force sword manufacturing method.

Here, as the electrolyte membrane 1, an anion exchange membrane or a cation exchange membrane is used. Or As the constituent material of the strong anion exchange membrane and cation exchange membrane, the anion exchange resin and the cation exchange resin contained in the precursor layer as necessary are used.

[0066] Further, the thickness of the electrolyte membrane 1 to be applied is preferably 10 to 300 µm.

[0067] The separator 5 is formed of a material having electronic conductivity, and examples of the material that can be used include carbon, resin-molded carbon, titanium, and stainless steel.

[0068] Further, the anode 20 can be manufactured in the same manner as the force sword 30 described above except that the potential applying step is not performed. The catalyst used for the anode catalyst layer 2 is preferably a noble metal alloy, a metal complex and / or a fired metal complex. As the noble metal alloy, in particular, Pt—Ru, which hardly causes poisoning of the catalyst, is preferable.

[0069] It should be noted that the potential applying step may also be performed when the anode catalyst layer 2 is formed. in this case

The conductivity of the anode 20 tends to be improved.

In the method of manufacturing the fuel cell 10, the fuel cell 10 includes the electrolyte membrane 1 sandwiched between the anode 20 and the force sword 30, and further sandwiched between the separators 5 and sealed with the gas seal body 6. It can produce by doing.

[0071] In the fuel cell 10 manufactured in this manner, the force sword is formed by the above-described method for manufacturing a power sword for a fuel cell, so that the current density is improved and the energy density of the fuel cell system is sufficiently high. Be improved. In addition, the cell voltage is sufficiently improved.

[0072] Further, the fuel cell 10 thus obtained can use various fuels such as hydrogen and methanol as reactants supplied to the anode 20, and can be suitably applied as PEFC or DMFC.

[0073] While the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments. For example, in the description of the above embodiment, the case where the force sword is composed of the catalyst layer and the diffusion layer has been described. Is also applicable.

[0074] In this case, the precursor layer serving as the precursor of the catalyst layer is formed by vapor deposition or coating on a substrate such as carbon paper, PET film, or PTFE film, or directly vapor deposited or coated on the electrolyte membrane 1. Can be formed. In this state, the precursor layer And a catalyst layer can be formed by performing an electric potential provision process.

When the catalyst layer is formed on the base material, the catalyst layer is transferred from the base material to the electrolyte membrane 1 when the fuel cell 10 is formed. The transfer can be performed by, for example, a method of bonding the catalyst layers 2 and 3 to the electrolyte membrane 1 by hot pressing or the like and then peeling the substrate.

Example

[0076] Hereinafter, the present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to the following examples.

[0077] [Example 1]

5, 10, 15, 20—Tetraphenylporphyrinatocobalt (II) (Aldrich Co.) is deposited on a glassy carbon 6mm φ disk electrode by vacuum deposition to produce a metal complex precursor. A body layer was formed. At this time, it was confirmed from the weight change before and after the vapor deposition that the coating amount of the metal complex was 20 μgZcm ² .

Next, a laminate in which a precursor layer is formed on the disk electrode is used as a working electrode, platinum is used as a counter electrode, a standard hydrogen electrode (SHE) is used as a reference electrode, and oxygen is used as an electrolyte. Using a saturated 0.5 M aqueous sulfuric acid solution, potential was applied to the laminate by sweeping the potential for 50 cycles at lOOmVZs in the range of 1.4 V to 0.05 V. Thus, a catalyst layer was formed, and the production of the electrode was completed. Figure 2 shows the relationship between the potential and the current density in the 50th cycle potential sweep.

[0079] [Example 2]

An electrode of Example 2 was produced in the same manner as Example 1 except that the potential sweep for the laminate was performed in the range of 1.6 V to 0.05 V. The relationship between the potential and the current density in the potential sweep at the 50th cycle in Example 2 is shown in FIG.

[0080] [Example 3]

As a metal complex, 20 mg of 5, 10, 15, 20-tetraphenylporphyrinatocobalt (II) (manufactured by Aldrich) was dissolved in 10 ml of N-methylpyrrolidone to prepare a coating solution. This coating solution was dropped onto a glassy carbon 6 mmφ disk electrode to form a uniform coating film and dried to form a precursor layer made of a metal complex. At this time, it was confirmed from the weight change before and after the formation of the precursor layer that the coating amount of the metal complex was 20 μg / cm ² . Next, a laminate in which a precursor layer is formed on this disk electrode is used as a working electrode, platinum is used as a counter electrode, a standard hydrogen electrode (SHE) is used as a reference electrode, and oxygen is used as an electrolyte. Using a saturated 0.5 M aqueous sulfuric acid solution, potential was applied to the laminate by sweeping the potential for 50 cycles at lOOmVZs in the range of 1.4 V to 0.05 V. Thus, a catalyst layer was formed, and the production of the electrode was completed.

[Example 4]

A coating solution was prepared by dissolving 20 mg of 5, 10, 15, 20-tetraphenylporphyrinatoiron (III) chloride (manufactured by Aldrich) in 10 ml of N-methylpyrrolidone as a metal complex. This coating solution was dropped on a glassy carbon 6mmφ disk electrode to form a uniform coating film and dried to form a precursor layer having a metal complex strength. At this time, it was confirmed from the weight change before and after the precursor layer formation that the coating amount of the metal complex was 20 μg / cm ² .

Next, a laminate in which a precursor layer is formed on the disk electrode is used as a working electrode, platinum is used as a counter electrode, a standard hydrogen electrode (SHE) is used as a reference electrode, and oxygen is saturated in an electrolyte. A 0.5 M sulfuric acid aqueous solution was used to apply a potential by sweeping the laminate for 50 cycles at 100 mV / s in the range of 1.4 V to 0.05 V. Thus, a catalyst layer was formed, and the production of the electrode was completed.

[0084] [Example 5]

A coating solution was prepared by dissolving 20 mg of nickel (II) phthalocyanine (manufactured by Aldrich) as a metal complex in 10 ml of N-methylpyrrolidone. This coating solution was dropped onto a glassy carbon 6 mmφ disk electrode to form a uniform coating film and dried to form a precursor layer made of a metal complex. At this time, it was confirmed from the weight change before and after the precursor layer formation that the coating amount of the metal complex was 20 μgZcm ² .

Next, a laminate in which a precursor layer is formed on the disk electrode is used as a working electrode, platinum is used as a counter electrode, a standard hydrogen electrode (SHE) is used as a reference electrode, and oxygen is used as an electrolyte. Using a saturated 0.5 M aqueous sulfuric acid solution, potential was applied to the laminate by sweeping the potential for 50 cycles at lOOmVZs in the range of 1.4 V to 0.05 V. This forms a catalyst layer, The production of the electrode was completed.

[0086] [Comparative Example 1]

An electrode of Comparative Example 1 was produced in the same manner as Example 1 except that no potential sweep was performed on the laminate.

[0087] [Comparative Examples 2 to 4]

The potential sweep for the laminate is 1.1V to 0.05V in Comparative Example 2, 1.3V to 0.05V in Comparative Example 3, 1.3V to 0.05V in Comparative Example 4. The electrodes of Comparative Examples 2 to 4 were produced in the same manner as in Example 1 except that the above steps were performed.

[0088] (Measurement of oxygen reduction current density)

For Examples:! To 5 and Comparative Examples:! To 4, the oxygen reduction current density at 0.05 V was measured. The results are shown in Table 1.

[0089] [Table 1]

[0090] As is apparent from the results shown in Table 1, the electrodes of Examples:! To 5 can obtain a significantly larger oxygen reduction current density than the electrodes of Comparative Examples:! To 4. confirmed.

[0091] (Evaluation of current density)

Using the electrodes of Examples 1, 4, 5 and Comparative Example 1 as rotating disk electrodes, cyclic voltammetry was performed at 100 mV / s in the potential range of 1.0 V to 0.05 V, and the oxygen reduction current density was It was measured. At this time, the electrodes of Examples 1, 4, 5 and Comparative Example 1 were respectively connected to the working electrode. The counter electrode was platinum, the reference electrode was a standard hydrogen electrode (SHE), and the electrolyte was an oxygen-saturated 0.5M aqueous sulfuric acid solution. Among these, FIG. 4 shows the relationship between potential and current density for each electrode of Example 1 and Comparative Example 1. At this time, even in the electrodes of Example 1 and Comparative Example 1 and the misaligned electrodes, a substantially constant current flows in the region where the potential is 0.2 V or less, and the critical diffusion current is reached. It was confirmed. Table 2 shows the current density at a rotational speed of 2500 rpm when the potential is 0.2 V when the electrodes of Examples 1, 4, and 5 and Comparative Example 1 are used.

[Table 2]

[0093] As is apparent from the results shown in Table 2, according to the electrodes of Examples 1, 4 and 5, compared with the electrode of Comparative Example 1, the oxygen reduction at 0.2 V (SHE standard) It was confirmed that the current density was improved.

From the above, it was confirmed that the current density of the obtained electrode can be improved according to the method for producing a power sword for a fuel cell of the present invention.

[0095] Further, according to the method of manufacturing a fuel cell of the present invention, the force sword is formed by the method of manufacturing the force sword of the present invention, so that the current density of the obtained fuel cell can be improved.

Industrial applicability

[0096] As described above, according to the present invention, a method for producing a power sword for a fuel cell capable of improving the current density, and a method for producing a fuel cell capable of improving the energy density. Can be provided.

Claims

The scope of the claims

[1] A method for producing a power sword for a fuel cell comprising a catalyst layer containing a catalyst,

Production of a power sword for a fuel cell, comprising a step of applying a potential to the precursor layer containing the catalyst by applying a potential nobler than 1.3 V with respect to a standard hydrogen electrode as a reference. Method.

2. The method for producing a fuel cell power sword according to claim 1, wherein in the potential application step, a potential of 1.6 V or less is applied to the precursor layer with reference to a standard hydrogen electrode.

[3] The method for producing a power sword for a fuel cell according to claim 1 or 2, wherein in the step of applying a potential, the potential is applied to the precursor layer by a potential sweep.

[4] The fuel cell cathode according to any one of claims 1 to 3, wherein the catalyst is a metal complex and / or a fired metal complex obtained by firing the metal complex. Manufacturing method.

5. The method for producing a fuel cell power sword according to claim 4, wherein the metal complex has a porphyrin ring or a phthalocyanine ring.

6. The metal complex is characterized in that the central metal is at least one metal selected from the group consisting of Co, Fe, Ni, Cu, Mn, V, and Ru. The manufacturing method of the power sword for fuel cells as described.

[7] A precursor layer forming step of forming the precursor layer by a coating method using a coating solution comprising the catalyst and a solvent capable of dissolving or dispersing the catalyst is included before the potential application step. The manufacturing method of the power sword for fuel cells as described in any one of Claims 1-6 characterized by the above-mentioned.

[8] A method for producing a fuel cell comprising an anode, a force sword, and a solid polymer electrolyte membrane disposed between the anode and the force sword,

A method for manufacturing a fuel cell, comprising an electrode forming step of forming the force sword by the method for manufacturing a power sword for a fuel cell according to any one of claims 1 to 7.